In prior art patents there are disclosed various methods and apparatus for applying locking patches of resilient resin to threaded articles. In the devices disclosed in these patents, generally a rotatable table or transport belts are disposed for receiving fasteners and transporting them through a plurality of stations to effect application of the patch to the threads of the threaded articles or the fastener elements.
U.S. Pat. Nos. 4,054,688 and 4,100,882 are directed to forming patches on fasteners whereby a portion of the heat fusible resin particles is deposited on one area of the hot threads of an element, and thereafter the resin particles are deposited on an additional area of the threads to produce two distinct patches at a desired location. In each of the aforementioned patents, internally threaded articles are retained on a rotatable support member in a selected position by means of a slot which receives a portion of the external surface of a hex head nut. After a discrete patch is applied to the internal threads of the fastener, a turning moment is applied to the fastener to move it such that a different external portion of the threads of the hexagonal element is received by the slot, after which a second discrete patch is applied to the threads of the fastener.
U.S. Pat. No. 3,858,262 is directed to a method and apparatus for making a self-locking threaded element which avoids the difficulties of resin deposit on the end faces of the threaded element and is effective to deposit resin on the selected threads with a minimum of spatter on other portions of the threads. In that method and apparatus as disclosed, a nut or other internally threaded member is heated. While the nut is mounted with its axis in an up-and-down position, the internal threads are sprayed with finely divided resin particles which are caught and built up on the heated surface to form a plastic body.
U.S. Pat. No. 3,894,509 is directed to an apparatus and method for mass production of internally threaded elements, including an automatic means to move a succession of the internally threaded elements through various stations in which the elements are loaded onto a conveying and treating member. A resilient resin locking patch is formed on the threaded surface of the elements by deposition of heat fusible resin powder and thereafter, the elements are unloaded.
U.S. Pat. Nos. 3,416,492 and 4,336,190 are directed to methods and apparatus wherein a self-locking internally threaded element is manufactured having a locking body of resilient resin provided over three hundred sixty degrees of arc of a portion of the internal threads.
Although substantial progress has been achieved in the above patents, it has become desirable to have an improved coated threaded article or coated fastener and a method of using the article which exhibits superior masking, lubricating and/or insulating characteristics. Furthermore, a superior size, shape and type of resin deposit or patch application, including the area of the deposit, shape of the resin spray deposited on the threads and application of the article in various fastening environments not previously obtainable by known fasteners or threaded articles is provided.
By way of example only, in an assembly line for the manufacture of automobiles, trucks and similar vehicles, line speed and uniformity are required in fastening parts together. In a vehicle assembly line, such parts include but are not necessarily limited to door panels, covering trim, fire walls, rugs, insulation and similar automotive parts. Traditionally these parts have been assembled by humans, as well as robots. As the vehicle passes a work station, parts are supplied to the worker which must be assembled into the passing vehicle. Typically, the worker assembles these parts with threaded fasteners and may use an automatic feeding and threading mechanism to install the fasteners.
In assembling parts, the automobile industry has traditionally relied on nuts and bolts, self-tapping and self-threading screws, as well as self-drilling screws. These methods have some inherent difficulties. For example, problems arise when a threaded fastener, such as a bolt or nut, is attached to a part prior to passing the work station. A part may contain a pre-drilled hole or an installed nut or bolt. When that part is dipped and/or sprayed with a corrosion inhibiting material, such as Uniprime or other rust inhibiting coverings, this type of material adheres to one or more of the threads of the fastener and makes fastening extremely difficult and time consuming. Another example can be seen in rugs and sound insulation which have typically been installed with self-drilling fasteners. The fibrous nature of such material commonly causes the fastener to bind in the material and/or increase the drive torque necessary to install the fastener. This results in slowing of the assembly line and/or sloppy installation of the parts. Difficulty has also been encountered in installing self-threading fasteners to attach two parts together. If the holes are not sized properly and/or substantially aligned, then an assembly line worker cannot install the fasteners in the allotted time.
To solve the problem of corrosion inhibitor build-up, the prior art has focused on applying a removable mask coating, such as a preformed cap or tape material, to substantially all of the fastener threads. This has met with only limited success and has not proven to be as safe and cost effective as desired. In attempting to solve the problem of reducing installation drive torque, lubricating coatings such as wax, cadmium wax and the like, have been used with only limited success and safety. These coatings have typically been expensive, inconvenient to apply, and at time have utilized hazardous or toxic materials. Consequently, it has been necessary to search further for an economical and convenient way to reduce the drive torque incurred during a fastening operation, to drill through fibrous materials and to prevent the unwanted adherence of materials such as rust inhibiting coatings to at least selected portions of the fasteners.
It is therefore an object of the present invention to provide an improved coated threaded article or fastener and a method of using the same having a functional resin type material deposited onto the threads of the threaded article or fastener.
A further object of the present invention is to provide an improved coated threaded article and method of using the threaded article wherein the article has an improved application or deposit of resin type material which is applied over a desired arcuate and vertical area of the threads of the article.
A still further object of the invention is to provide a threaded article and method of use having improved definition of the resin type material which is applied over a desired arcuate and vertical area of the threads of the threaded article.
It is also an object of this invention is to provide a coated threaded article having a coating which protects, insulates or masks the threads from unwanted contamination or deposition of material thereon.